Flexible medical device with marker band and sensor

ABSTRACT

A system and method for determining a pH level of blood in a vessel of a patient including a flexible elongated device configured and dimensioned for insertion in the vessel of the patient. The elongated device has a tubular portion, a marker band positioned distally of the tubular portion and a pH sensor positioned within the marker band to measure the pH level of blood downstream of the blood clot and an indicator to indicate the measured pH.

BACKGROUND

This application claims priority from provisional application Ser. No.62/313,711, filed Mar. 26, 2016, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

This application relates to a flexible medical device, and moreparticularly to a flexible medical device with a sensor.

BACKGROUND OF RELATED ART

Cerebrovascular disease refers to diseases of the brain caused byvascular abnormalities which result in abnormal cerebral blood flow. Themost common cause of cerebrovascular disease is narrowing of the majorarteries supplying blood to the brain, resulting in thrombogenic diseaseor sudden occlusion of blood flow, which if large enough results inischemic stroke.

Clots (Ischemic Stroke) can originate in various areas and be caused bydifferent modalities. These different modalities create clots that varyin consistency. The clot can be platelet rich (runny) or fibrin rich(hard) or anywhere in between the two. Ischemic stroke is caused by thethrombosis of a major vessel supplying blood to a region of the brain. Ashortage of blood in the cerebral tissue leads to the deletion ofmetabolites such as oxygen and glucose, which in turn causes depletionof energy stores of the cells. Therefore, it is critical to remove theclots to restore adequate blood supply to the brain.

Current treatments for clot removal include application of thrombolyticdrugs to dissolve the clot, aspiration, and mechanical thrombectomydevices in minimally invasive procedures. A problem encountered withthese approaches is that the composition of the clot is undetectable insitu, while the efficacy of these approaches is dependent in part on theclot composition. Therefore, the physician is taking one of the knownapproaches for treatment of the clot without the knowledge of the clotmakeup, e.g., its consistency. This can lead to inconsistent results aswell as failure to properly treat the clot.

It would therefore be beneficial if the surgeon could identify the typeof clot beforehand to better assess how the clot could be treated. Suchprior knowledge would greatly enhance clot removal as the surgeon canadapt the approach to better match the treatment device or drugs withthe type of clot.

Although techniques for identifying characteristics of blood clots areknown, the need exists for a simple, reliable, easy to use and lowprofile system for clot assessment. It would also be beneficial toprovide such system which can effectively assess blood clotcharacteristics at various times during the procedure.

Moreover, in addition to determining the type of blood clot, it wouldalso be beneficial to assess whether the blood clot has been effectivelyremoved during the procedure without relying on current methods, such asinjecting contrast, which can have adverse effects such as re-compactingthe clot.

In addition, in cerebrovascular disease, the vitality of the vasculaturedistal to the clot is compromised once the clot lodges in place.Vasculature that has been deprived of oxygenated blood will necrose andbecome friable. Once blood flow is restored after clot removal, suchblood flow could potentially cause a hemorrhagic event, which means thevessel can bleed out and burst open. Currently, surgeons do not haveadequate knowledge of the vasculature downstream of the clot andtherefore cannot accurately assess the risk of clot removal by forexample dissolution, aspiration or mechanical thrombectomy.

It would be beneficial if the surgeon could determine the health of thevasculature distal to the clot prior to removal of the clot so thesurgeon could determine if clot removal is advisable and/or takenecessary precautions during clot removal so the vessels are notcompromised. Prior attempts to measure pH using magnetic resonanceimaging (MRI) technique have been attempted, as explained for example in“Modelling of pH Dynamics in Brain Cells After Stroke”, by PiotrOrlowski, et al., published in Interface Focus, The Royal Society, 2011.However, these attempts to date have been unsuccessful. Additionally,relying on MRI is very expensive and requires relatively complexmathematical models. Further, an ischemic event might need to be treatedin an ambulance prior to arrival at a hospital and thus an MRI is notpossible. Therefore, although the role of pH of the vasculature isrecognized, the need exists to utilize this parameter to readily andinexpensively determine in hospital and non-hospital settings vasculartissue health to enhance blood clot removal or avoid clot removal wherethe risk is too great. This would provide great benefits not only forhospital treatment but for pre-hospital treatment such as in theambulance or home prior to arrival at the hospital.

Additionally, after assessment of the health of the vasculature andselection of the proper clot treatment, it might be beneficial tocontrol the restoration of blood flow. Being able to determine thehealth of the vasculature would thus advantageously enable gradualreturn of blood flow if deemed necessary to reduce the risk ofhemorrhaging.

In treating cerebral arteries and other small arteries in the body, thechallenge is to provide a device of sufficiently small size to navigatethe small vessels and fit within the small vessel lumen while balancingthe competing features of sufficient flexibility to navigate thetortuous vasculature and sufficient rigidity to enable pushability tothe target site. The challenge of small size is exacerbated when thedevice needs to carry a sensor for detecting blood/vessel parametersand/or blot clot parameters.

SUMMARY OF THE INVENTION

The present invention provides in one aspect a system for determining apH level of blood in a vessel of a patient comprising a flexibleelongated device configured and dimensioned for insertion in the vesselof the patient and having a proximal portion, a distal portion and atubular portion having a lumen formed therein. The elongated device isconfigured for insertion so the distal portion extends past a blood clotfor positioning of the distal portion distal of the blood clot. A markerband is provided, at least a portion of which is positioned distally ofthe tubular portion. A sensor for positioning distal of the blood clotis positioned within the marker band. A connector operably connects thetubular portion to an indicator, the sensor measuring the pH level ofblood downstream of the blood clot to thereby determine pH of the vesseldownstream of the blood clot to determine the condition of the vessel toassess subsequent treatment of the blood clot, the indicator providingan indication of the pH measured by the sensor.

In some embodiments, the tubular portion comprises a hypotube. In someembodiments, the tubular portion has a first wall thickness and themarker band has a second wall thickness, the second wall thickness beingless than the first wall thickness. In one exemplary embodiment, thefirst wall thickness is between about 0.002 inches and about 0.004inches and the second wall thickness is between about 0.001 inches andabout 0.002 inches. In some embodiments, the tubular portion has amartensitic distal region and an austenitic proximal region.

In some embodiments, the tubular portion has a first outer diameter andthe marker band has a second outer diameter substantially equal to thefirst outer diameter. The marker band can in some embodiments have awindow or cutout to enable communication of the sensor with the blood inthe vessel. In some embodiments, the tubular portion has a first reduceddiameter region at the distal region, and a radiopaque coil ispositioned on the first reduced diameter region. In some embodiments, asecond marker band is positioned proximal of the first marker band. Insome embodiments, the tubular portion has a second reduced diameterregion formed proximal of the first reduced diameter region to support avascular implant. In some embodiments, the sensor has a wire extendingthrough the lumen of the tubular portion.

In some embodiments, the system includes a second sensor for sensing aparameter of the blood clot and a second indicator to indicate thesensed parameter, the second sensor connected to the second indicator.In some embodiments, the second sensor senses a density of the bloodclot.

In accordance with another aspect of the present disclosure a system fordetermining a pH level of blood in a vessel of a patient is providedcomprising a flexible elongated device configured and dimensioned forinsertion in the vessel of the patient, the elongated device having aproximal portion, a distal portion and a tubular portion having a lumenformed therein. The elongated device is configured for insertion so thedistal portion extends past a blood clot for positioning of the distalportion distal of the blood clot, the elongated device having a lumenformed therein. A sensor is carried by the flexible elongated device forpositioning distal of the blood clot. A locator on the elongated deviceindicates a position of the sensor within the vessel and an indicatorpositioned outside the patient communicates with the sensor, theindicator indicating a measured parameter of the blood.

In some embodiments, the sensor measures a pH level of the blooddownstream of the blood clot to determine the condition of the vessel toassess one or both of a) treatment of the blood clot in response to thepH level indicated by the indicator; and b) desired blood flow rateafter blood clot removal. In some embodiments, the locator is a markerband positioned distal of the tubular portion, the sensor positionedwithin the marker band and the marker band having a window to enablecommunication of the sensor with the blood. In other embodiments, thesensor measures the density of the clot. In some embodiments, thelocator includes a first radiopaque coil positioned on the tubularportion and a second radiopaque coil positioned on the tubular portionproximal of the first radiopaque coil, and a gap is formed between thefirst and second radiopaque coils forming an exposed region having awindow, the sensor positioned within the tubular portion and alignedwith the window.

In accordance with another aspect of the present invention a method fordetermining a pH level of blood downstream of a blood clot in a vesselof a patient is provided comprising the steps of:

providing an elongated flexible device having a radiopaque marker bandand a sensor positioned within the marker band;

inserting the flexible device through vasculature of the patient andpast the blood clot to a position downstream of the blood clot in thevessel, the marker band indicating to the user the position of thesensor;

sensing a pH level of the blood downstream of the blood clot; and

indicating to the user the pH level of the blood to enable the user todetermine a pH level of the vessel downstream of the blood clot forsubsequent selection of a clot treatment method.

In some embodiments, the method further comprises the step ofdetermining a density of the blood clot to determine a clot treatmentmethod. In some embodiments, a connector is provided connecting theflexible device to a visual indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present disclosure are described hereinwith reference to the drawings wherein:

FIG. 1 is a side view of a first embodiment of the system of the presentinvention illustrating a catheter coupled to a pH reader and showing thecatheter tip positioned distal of the blood clot;

FIG. 2A is a close up perspective view of the pH reader of FIG. 1;

FIG. 2B is a close up perspective view of an oxygen level reader;

FIG. 3A is a close up view of the catheter tip of FIG. 1 showing the pHsensor on an outer surface of the catheter for determining blood pH;

FIG. 3B is a close up view of the catheter tip showing the pH sensorembedded in the wall of the catheter in accordance with an alternateembodiment;

FIG. 4 is a close up perspective of the coupler of FIG. 1 for connectingthe pH reader cable to the catheter;

FIG. 5 is a close up view of the vasculature illustrating the cathetertip of FIG. 1 positioned past a blood clot;

FIG. 6 is a side view of an alternate embodiment of the system of thepresent invention illustrating a guidewire coupled to a pH reader andshowing the guidewire positioned distal of the blood clot;

FIG. 7 is a close up perspective view of the coupler connecting the pHreader cable to the guidewire;

FIG. 8A is a close up view of the guidewire of FIG. 6 positioned distalof the clot and showing the pH sensor on the outer tip of the guidewire;

FIG. 8B is a cutaway view showing the pH sensor embedded in the wall ofthe guidewire in accordance with an alternate embodiment;

FIG. 8C is a close up view of an alternate embodiment having a pH sensorspaced from the distal tip;

FIG. 9A is side view of an alternate system of the present inventionillustrating a catheter coupled to a density reader and showing thecatheter tip positioned distal of the blood clot;

FIG. 9B is a close up view of the distal portion of the catheter of FIG.9A showing the density sensor within the clot;

FIG. 10 is a close up view of the density reader of FIG. 9A showing aclot density reading;

FIG. 11A is a side view of an alternate embodiment of the system of thepresent invention illustrating a guidewire coupled to a density readerand showing the guidewire positioned distal of the blood clot;

FIG. 11B is a close up view of the distal portion of the guidewire ofFIG. 11A, with the clot broken away to show the density sensor withinthe clot;

FIG. 12A is a side view of another alternate system of the presentinvention showing a catheter coupled to a pH reader and a guidewirecoupled to a density reader, and further showing the catheter tip andguidewire positioned distal of the blood clot;

FIG. 12B is a close up view of the distal end of the catheter andguidewire of FIG. 12A, showing retraction of the catheter to expose thedensity sensor on the guidewire;

FIG. 13 is an enlarged view of the density and pH reader of FIG. 12A;

FIG. 14A is a side view illustrating the introducer sheath positioned inthe femoral artery and the guide catheter shown advanced into thecerebral artery;

FIG. 14B is a side view similar to FIG. 14A showing the guidewire of thepresent invention advanced through the guide catheter and past thecerebral blood clot;

FIG. 14C is a side view similar to FIG. 14B showing a microcatheter fortreating the blood clot advanced over the guidewire, and further showingthe balloon of the microcatheter inflated to cause slow reperfusion asthe blood clot is removed;

FIG. 14D is a side view similar to FIG. 14C showing an alternateembodiment of a microcatheter for treating the blood clot advanced overthe guidewire, and further showing the injection of cryogenic fluid toenable slow reperfusion as the blood clot is removed;

FIG. 14E is a side view similar to FIG. 14C showing an alternateembodiment of a microcatheter for treating the blood clot advanced overthe guidewire, and further showing the balloon of the microcatheterinflated as the blood clot is removed;

FIG. 14F is a side view similar to FIG. 14E showing an alternateembodiment with a balloon on the guide catheter;

FIG. 15 is an exploded perspective view of an elongated flexible devicein accordance with an alternate embodiment of the present invention;

FIG. 16 is an exploded perspective view of the distal region of theflexible device of FIG. 15;

FIG. 17 is an exploded perspective view of the distal region of theflexible device of FIG. 15;

FIG. 18 is a perspective view of the flexible device of FIG. 16;

FIG. 19 is a side view of the flexible device of FIG. 15;

FIG. 20A is an enlarged perspective view of the distal region of theflexible device of FIG. 15;

FIG. 20B is a perspective view of the distal region of an alternateembodiment of the flexible device.

FIG. 21 is a side view of an alternate embodiment of the flexible deviceof the present invention having a reduced diameter region to support avascular implant;

FIG. 22 is a side view of another alternate embodiment of the flexibledevice of the present invention having a reduced diameter region;

FIG. 23 is a perspective view of the distal portion of another alternateembodiment of the flexible device of the present invention;

FIG. 24A is a flow chart showing the steps for density measurement andindication in accordance with one embodiment of the present invention;

FIG. 24B is a flow chart illustrating the method steps for densitytracking of the blood clot in accordance with one embodiment of thepresent invention; and

FIG. 25 is a close up view of an alternate embodiment of the densityreader of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a system for determining the type ofblood clot. This enables the clinician to assess the best mode oftreatment of the blood clot. The present invention further provides asystem which can track blood clot removal. The present invention alsoprovides a system for determining the health or condition of thevasculature distal of the blood clot. This aids the clinician inassessing the effect of removal of the blood clot from the vessel. Thiscan also enable the clinician to assess the rate of reperfusiondesirable post clot treatment. The foregoing systems can be usedindependently, or alternatively, two or more of the foregoing systemscan be used together. That is, it is contemplated that only one of thesystems is utilized so the user measures only one of the parameters,e.g., health of vasculature or type of clot. However, it is alsocontemplated that two or more of the systems can be utilized so the usercan determine the foregoing parameters plus determine, if desired, ifthe clot has been effectively removed and/or a desired rate ofreperfusion. These systems are described in detail below.

Vasculature Determination

Turning first to the system for determining the health or condition ofthe vasculature, this system is illustrated in FIGS. 1-8, with FIGS. 1-5illustrating an embodiment where the pH sensor is located on a catheterand FIGS. 6-8B illustrating an embodiment where the pH sensor is locatedon a guidewire. It is also contemplated that a pH sensor can bepositioned on the catheter and on the guidewire, and it is alsocontemplated that one or more pH sensors can be positioned on thecatheter and one or more pH sensors can be positioned on the guidewire.Multiple sensors would enable different regions of the blood (andtherefore the vasculature) to be measured. In certain embodiments,utilizing multiple pH sensors, the sensors can be spaced apartsufficiently so that a pH measurement can be taken both upstream anddownstream of the blood clot for comparative purposes in assessingvasculature health.

The system for measuring pH is beneficial since in certain instances thevitality of the vasculature distal to the blood clot is compromised oncethe clot lodges in place. Vasculature that has been deprived ofoxygenated blood will necrose and become friable. Once blood flow isrestored after clot removal, such blood flow could potentially cause ahemorrhagic event, which means the vessel can bleed out and burst open.Therefore, this system provides a way of determining the health of thevasculature distal to the clot so the physician could determine if clotremoval is advisable to determine the best method to remove the clot ortake other precautions during clot removal. That is, the physician willbe able to determine if the clot should be removed based upon the pHcontent of the vasculature distal to the clot, and if removal isdesirable, assess the best way to restore blood flow as the clot isremoved.

Such determination can be done measuring pH of the blood. Thus, the pHlevel of blood, measured in a simplified cost effective mobile andefficient manner, is utilized to assess the condition of the vessel.That is, measuring the pH level of blood will provide the pH level ofthe vessel by the clot.

Note the vasculature health can also be accomplished in an alternateembodiment by sensing oxygen levels in the blood which would provide anindication of the health of the vasculature. Other parameters could alsobe measured.

With respect to pH, it is understood that intracellular pH is importantin the maintenance of normal cell function. Blood pH is regulated by asystem of buffers that continuously maintain its normal range of 7.35 to7.45. Blood pH drop below 7 or above 7.45 can cause serious problems,including death. Studies have shown that carbon dioxide plays a vitalrole in blood pH abnormality. Carbon dioxide serves as a buffer. Ascarbon dioxide becomes depleted, the pH drops and acidosis and/orapoptosis occurs.

With the presence of a blood clot, there is essentially a closed system(or substantially closed system) created in the vasculature since bloodflow downstream of the clot has mostly stopped. Being a closed system,the pH of the blood can be measured and the blood pH will be indicativeof the pH of the adjacent vasculature. Thus, the measurement of theblood pH as described herein provides an inexpensive, accurate andeffective way to determine (i.e., measure) the pH and thus the health ofthe adjacent vasculature. The blood pH can be measured utilizing knowntechniques such as an ionic potential sensor that converts the activityof a specific ion dissolved in a solution into an electric potentialwhich can be measured. Known glass and crystalline membranes can beutilized. The sensor can be contained in a microchip. Fiber opticstransmission can also be utilized.

It is also contemplated that instead of measuring blood pH, the oxygenlevel of the blood can be measured downstream of the blood clot,preferably in a closed or substantially closed system, to therebydetermine the health of the vasculature.

The system of the present invention provides a quick and simpleeffective measurement of the blood downstream of the clot and enables adetermination of blood clot treatment either during or prior tohospitalization, such as in the ambulance ride, wherein the treatmentmethod can be determined so as to prevent cerebral hemorrhaging. This isaccomplished without expensive and cumbersome equipment such as MRImachines.

The system in some embodiments not only enables determination of theoptimized treatment of the blood clot but in cases where it determinesblood clot removal is indicated, it enables control of reperfusion. Thatis, based on the pH measurement, it provides an indication whetherrestoration of normal blood flow as a result of clot removal isacceptable, i.e., whether the vessel is in condition to handlerestoration of normal blood flow, or whether restoration of blood flowneeds to be controlled, i.e., delayed and/or restored slowly until thepH level rises to an acceptable level. Several ways to controlreperfusion are discussed below by way of example. Note that the systemfor measuring pH can be utilized prior to, during and after blood clottreatment to provide indications of pH levels of the blood and thus thevasculature at various times.

Turning more specifically to the system of FIGS. 1-5, catheter 10 has aproximal portion 12 and a distal portion 14. The catheter tube 16 issufficiently flexible to navigate the small vessels while having somerigidity to enable it to be directed around the curves of thevasculature. An RHV (rotating hemostatic valve) 20 is attached to thecatheter hub 22 and includes a side arm 24 for fluid injection and/oraspiration. Coupler (connector) 30 is attached to the catheter 10, andis connected to cable 34 which is connected to pH reader (meter) 40. Inone embodiment, as shown in FIG. 4, the coupler 30 is u-shaped withopening 31 between the legs of the “u” dimensioned to frictionally clamponto the outer wall of the catheter 10. That is, the coupler 30 is shownin the embodiment of FIG. 1 in the form of a U-shaped clip with theradius of the U smaller than that of the outer wall of the catheter soit flexes outwardly when placed over the strain relief of the catheterand then is frictionally retained on the catheter. In anotherembodiment, a second connector (coupler) half is placed opposite theconnector to form a 360 degree clip or clamp surrounding the outer wallof the catheter to retain the connector on the catheter 10. Othermethods of attachment are also contemplated such as magneticattachments. Cable 34 is connected to the coupler at one end 35 andconnected at the opposing end 36 to reader 40. As shown (FIG. 1), thecoupler 30 is attached to the region of catheter 10 just distal of hub22, although other locations are also contemplated. The coupler 30 canbe attached to the strain relief of the catheter 10 to enhance coupling.

The pH sensor 26 for measuring blood pH is positioned at the distalportion 14 of the catheter 10 and is electrically coupled to cable 34via a pair of wires (not shown) extending from the sensor 26 to thecoupler 30 and/or cable 34. The wires can be embedded in a wall of thecatheter 10 or alternatively extend through a lumen in the catheter 10.In the embodiment of FIG. 3A, the sensor 26 is positioned on an outerwall of the catheter 10, extending circumferentially around 360 degrees.The sensor can also be incorporated into a marker band at the tip of thecatheter 10 as discussed in detail below. In the alternate embodiment ofFIG. 3B, the sensor 26′ is positioned inside the catheter 10, eitherinternal of the inner catheter wall or alternatively embedded in thewall of the catheter 10′. Wires 27 connect the sensor 26′ to the coupler30 and/or cable 34, with two lines coming into the reader 40 andextending to the sensor 26.

The pH reader 40 provides an indicator device and contains an on offswitch 42. A reading 44 provides a visual indication, as a numericvalue, of the measured pH of the blood to inform the user of the pH ofthe blood, and therefore the vasculature. FIG. 2 shows by way of examplea reading of 6.4 which is below the normal range of 7.35 to 7.45 andthus indicates acidosis has likely occurred which affects (compromises)the vasculature structure.

In some embodiments, a pH level of 6.8 of the blood/vasculature is usedas the parameter to modify the treatment modality. In other embodiments,the pH level of 6.4 is used as the parameter to modify the treatmentmodality. By way of example, 6.8 could be a first predetermined levelwhere if the measured pH is at or below this level, the clinician woulddecide that blood clot removal provides some risk and the method of clotremoval needs to be assessed. By way of example, 6.8 could be thethreshold for assessing the type of treatment method and a pH level of6.4 could be the predetermined level where the clot should not beremoved because of the condition of the vasculature. In otherembodiments, 6.0 could be the predetermined level at which the clotwould not be removed.

In some embodiments, a pH level of 6.8 of the blood/vasculature is usedas the parameter to modify post treatment reperfusion. In otherembodiments, the pH level of 6.4 is used as the parameter to modify posttreatment perfusion. By way of example, 6.8 could be a firstpredetermined level where if the measured pH is at or below this level,the clinician would decide that blood flow restoration post blood clotremoval is at risk and blood flow needs to be controlled to graduallyrestore blood flow. By way of another example, 6.4 can be the thresholdfor assessing the treatment method if the measured pH is at or belowthis level, the clinician would decide that blood flow restoration postblood clot removal is at risk and blood flow needs to be controlled togradually restore blood flow.

Current treatments for clot removal include application of thrombolyticdrugs to dissolve the clot, aspiration of the clot and mechanicalthrombectomy devices in minimally invasive procedures. A problemencountered with these approaches is that the composition of the clot isundetectable in situ, while the efficacy of these approaches isdependent in part on the clot composition. Therefore, the physician istaking one of the known approaches for treatment of the clot without theknowledge of the clot makeup, e.g., its consistency. This can lead toinconsistent results as well as failure to properly treat the clot.

In use, the catheter 10 (or 10′) can be inserted utilizing knownmethods, e.g., through a femoral approach or a brachial approach, andadvanced through the vascular system to the desired treatment site, e.g.a cerebral artery A. The catheter tip 11 is advanced past the blood clotC (see e.g., FIG. 5). The sensor is activated to measure pH, with the pHreader turned on so that pH value can be determined. As noted above, theclosed system advantageously enables the user to determine thevasculature condition, i.e., the pH of the vasculature by measuring theblood pH rather than the pH of the vasculature itself. Proper treatmentapproaches, e.g., deciding whether the clot can be safely removed,selecting the safest clot removal method or taking other precautions toprotect the vessel, can then be implemented. Also, restoration of bloodflow can then be controlled in accordance with the condition of thevessel.

FIGS. 6-8B illustrate an alternate embodiment for measuring pH utilizinga sensor on a guidewire instead of the catheter as in FIG. 1. Thisprovides a reduced profile measurement system. It also provides a moreflexible system to navigate tortuous vessels. Also, by being smaller itcan be inserted more distal within the cerebral vasculature. It couldalso be more steerable and could traverse the clot easier. In someembodiments, by way of example, the outer diameter of the guidewire canbe between about 0.010″ and about 0.032″, although other ranges of sizesare also contemplated. In some embodiments, the outer diameter can beabout 0.014″.

Guidewire 50 has a proximal portion 52 and a distal portion 54. Theguidewire 50 is sufficiently rigid to navigate the small vessels whilehaving some rigidity to enable it to be directed around the curves ofthe vasculature. In one embodiment, the guidewire is hollow to form alumen and the wire(s) runs through the lumen from the sensor to theconnector. The wire(s), as in other embodiments herein, is preferablyinsulated. In another embodiment, the guidewire is a solid core and apolymeric jacket contains the insulated wire(s) on an outer surface ofthe guidewire. The guidewire 50 is illustrated within a lumen of acatheter 70 having a RHV 74 attached to the proximal end. The RHV 74 isattached to the hub 72 of the catheter 70 and includes a side arm 75 forinjection and/or aspiration. Coupler 80 is attached to the guidewire 50,and is connected to cable 83 which is connected to pH reader 40, thusconnecting the wire(s) of the sensor to the cable and reader 40. The pHreader can be the same as in the embodiment of FIG. 1. In oneembodiment, as shown in FIG. 7, the coupler (connector) 80 is u-shapedwith opening 81 between the legs of the “u” dimensioned to frictionallyclamp onto the outer wall of the guidewire 50. A two part connector asdescribed above could also be utilized. Other methods of attachment arealso contemplated including magnetic attachments for example. Cable 83is connected to the coupler 80 at one end 85 and connected at theopposing end 86 to reader 40.

The pH sensor 56 is positioned at a distal end of the guidewire 50 andis electrically coupled to coupler 80 and/or cable 83 via a pair ofwires (not shown) extending from the sensor 56. The wires can beembedded in a wall of the guidewire 50, or alternatively, the guidewirecan have a lumen or channel through which the wires extend. In theembodiment of FIG. 8A, the sensor 56 is positioned on an outer wall ofthe guidewire 50, extending circumferentially around 360 degrees. Thesensor can also be incorporated into a marker band at the tip of theguidewire 50 as described below. In an alternate embodiment, the sensor56′ and wires 57 (only one is shown) of guidewire 50′ can be positionedinside the guidewire 50′, either internal of the inner wall of theguidewire as shown in FIG. 8B, or alternatively embedded in the wall ofthe guidewire. The catheter 70 through which the guidewire extends canhave a marker band 79 for imaging. Note in FIG. 8A, the catheter 70 andguidewire 50 are positioned in a cerebral artery A distal of clot C.

In use, the switch 42 of the pH reader 40 is activated and the sensor 56is activated to measure the blood pH and the pH reader provides anumeric pH value of the blood, which is indicative of the pH level ofthe vasculature. FIG. 6 shows a pH reading of 6.4 by way of example.Note the guidewire 50 can be inserted utilizing known methods, e.g.,through a femoral approach or a brachial approach, and advanced throughthe vascular system to the desired treatment site, e.g. the cerebralartery. In one method, first an introducer is placed in the femoralartery, and a large guidewire and guide catheter is advanced to thecarotid artery. The large guidewire is removed, and replaced with amicrocatheter 70 and a smaller dimensioned guidewire 50 of the presentinvention which contains sensor 56. The catheter tip 71 (containingmaker band 79 for imaging) of catheter 70 and guidewire tip 51 areadvanced past the blood clot C (see e.g., FIG. 8A). The sensor 56measures the pH and transmits the measurement through the wiresextending in guidewire 50 back to the cable 83 which in turn transmitsit to the reader 40. As noted above, the closed system advantageouslyenables the user to determine the vasculature condition by measuring theblood pH rather than the pH of the vasculature (or surrounding tissue)itself. Proper treatment approaches for the treating the blood clot canthen be better selected. That is, the physician can determine whetherremoval of the clot would be too traumatic to the vessel and riskhemorrhaging. The physician can also determine the safe restoration ofblood flow and control such blood flow in accordance with the conditionof the vessel. Note the different parameters described above areapplicable to this embodiment (sensor on the guidewire) as well.

Note the sensors are shown at the distalmost tip of the catheter (FIGS.1-5) or guidewire (FIGS. 6-8B) but alternatively can be spaced proximalof the distalmost tip such as the sensor 56 a of guidewire 50 a of FIG.8C.

The pH sensors can be used in other applications such as in cases ofgangrene or tissue dying for some other reason to intravascularly assessthe vasculature or health of the tissue.

In an alternate embodiment, the oxygen level of the blood can bemeasured which is indicative of the oxygen and thus the health of thevasculature due to the closed or substantially system closed systemresulting from the blood clot. The system would be the same as with theabove described systems, except one or more oxygen sensors (rather thanpH sensors) would be provided on the catheter and/or the guidewire andconnected to an oxygen reader (meter) such as shown in FIG. 2B. Theoxygen reader provides an indicator of the oxygen level, by providingfor example a numeric value, or other indicator, to indicate a range oflow to high oxygen level measurements. The sensors can be positioned onthe catheter or guidewire in the similar manners of the pH sensorsdisclosed herein.

FIGS. 15-23 illustrate alternate embodiments of the flexible elongateddevice which supports or carries the sensor. The flexible elongateddevice includes a hypotube dimensioned for insertion through cerebralarteries or other small vessels. The sensor in these embodiments iscarried distal of the hypotube to minimize the outer diameter of thedevice. Further, radiopaque markers or indicators are provided toidentify the sensor location. Various embodiments are disclosed whichachieve this minimization while still optimizing the balance betweenflexibility for navigating the tortuous vasculature and rigidity forpushability/directability through the vasculature to the target site.

Turning first to the embodiment of FIGS. 15-20, the flexible elongateddevice is designated generally by reference numeral 400 and includes atubular portion 402 in the form of a hypotube. Tubular portion(hypotube) 402 has a distal region 404, a proximal region 406 and anintermediate region 408 (note the broken lines in FIG. 15). A lumen 410extends through the tubular portion 402 to receive the wires 413 fromthe sensor 412. In some embodiments, the proximal region 406 of thehypotube 402 is superelastic, the distal end 404 is non-superelastic andthe intermediate region 408 forms a transition region between regions404 and 406. That is, the proximal region 406 can be austenitic and thedistal region 404 can be martensitic. The superelastic material ispreferably Nitinol, with a transition temperature greater than bodytemperature, although other materials are also contemplated. Thus, inthis embodiment, the proximal region 406 is austenitic to provide aharder region and the distal region 404 is martensitic to provide asofter region that is shapeable and trackable. In the embodiment shown,the tubular portion 402 does not have a taper but relies instead on thechanging properties along its length to achieve trackability. However,in alternate embodiments, the tubular portion 402 can have a tapereddistal region to increase flexibility at the distal region.

As shown in FIGS. 15 and 16, the tubular portion 402 has a stepped downtransition or transition zone 414 to transition from a larger diameterat the intermediate and proximal regions 408, 406, respectively, to asmaller diameter region 405 in the distal region 404 distal of thetransition 414. In some embodiments, by way of example, the intermediateand proximal regions 408, 406, which are proximal of the transition 414,have an outer diameter of about 0.018 inches and the distal region 404distal of the transition 414 has an outer diameter of about 0.014inches. Other dimensions are also contemplated. In addition, inalternate embodiments, the hypotube can be formed of multiple diameters.The smaller diameter region 405 can be formed by cutting out a portionof the hypotube 402, by swaging, grinding or other known methods. Notefor ease of manufacture, in some embodiments, it is contemplated thatthe proximal region 406 can be a standard size and the reduced diameterdistal region 405 can be of varying sizes to accommodate differentclinical applications. That is, in these embodiments, variable sizedhypotubes can be provided, with each having a different diameter distalregion but the same size diameter proximal region.

Positioned over the reduced diameter region 405 is a coil 420. Thereduced diameter 405 and coil 420 can be of various lengths but in oneembodiment by way of example they are about 3 cm long, with the hypotube402 having an overall length of about 165 cm. Other dimensions are alsocontemplated. When the coil 420 is seated over the reduced diameterdistal region 405, it increases the diameter of the tubular portion 402,preferably to an extent such that the outer diameter of the distalregion 404 is substantially equal to the outer diameter of the proximalregion 406 to provide a substantially uniform outer diameter of theelongated device 400 for a smooth transition. The coil 420 is preferablycomposed of a radiopaque material such as platinum. As shown, the coilpreferably extends from the transition zone 414 to the distalmost tip409 of hypotube 402.

A marker band 422 is attached to the tubular portion 402. One method ofattachment is securement of proximally extending tab 423 of marker band422 (FIG. 16) within slot 407 of tubular portion 402 where it is thensoldered or welded. The tab and slot arrangement help orient the markerband. Note, the tab, shown extending linearly, can have an upward bendto help maintain its position and orientation with respect to thetubular portion. Other methods of attachment are also contemplated toattach marker band 422 so it extends distally of the distalmost tip 409of the tubular portion 402. Positioned within marker band 422 is asensor 412. Thus, the marker band 422 and sensor 412 are positioneddistal of the coil 420 and tubular portion 402. Sensor 412 is supported(carried) within marker band 422 by epoxy, a tight fit, silicone orother known methods. The sensor 412 in some embodiments can be in blockform having height, width and length dimensions by way of example ofbetween about 0.007 inches and about 0.008 inches, although otherdimensions are also contemplated to fit within the internal diameter ofthe marker band 422. The marker band 422 preferably has a thin wallwhich is thinner than the wall of the tubular portion 402 and in someembodiments by way of example is between about 0.001 inches and about0.002 inches while the wall of the tubular portion is between about0.002 inches and about 0.004 inches. By placing the sensor 412 withinthe marker band 422 as in this embodiment, there is more room for sensorplacement not only because the marker band 422 has a larger outerdiameter and larger inner diameter than the reduced diameter distalregion 405 of hypotube 402, but the marker band 422 has a thinner wallthan the wall of the hypotube 402. This results in a larger internaldiameter than the tubular portion 412. Stated another way, the markerband 422 and tubular portion 402 preferably have a substantially equalouter diameter except for the reduced diameter region, where the markerband has a substantially equal diameter to the coil 420 positioned overthe distal region of the tubular portion 402. This provides a smoothouter region for insertion though the vasculature. (Note the proximalend of the marker band 422 can abut the distal end of the coil 420).Since the tubular portion 402 should have sufficient rigidity forpushability, its wall should have a sufficient thickness to provide suchstructural rigidity. Such wall thickness reduces the inner diameter ofthe tubular portion 402, thus leaving less room for the sensor. Themarker band 422, placed at the distal tip of the device 400, does notneed to have such rigidity so it can be provided with a thinner wall tothereby leave more internal space for a sensor. Thus, by placementwithin the marker band, a larger sensor can be accommodated.Additionally, the radiopacity of the marker band 422 provides visibility(e.g., under X-ray fluoroscope) to inform the clinician of the locationof the sensor within the body lumen since the sensor 412 in theseembodiments is located within the marker band 422. Note in alternateembodiments, the sensor need not be placed within the marker band, but,for example, if sufficiently small enough, could be placed for examplein the tubular portion. Any of the various sensors disclosed herein canbe positioned within the marker band.

Wires 413 extend from sensor 412 and through lumen 410 of tubularportion 402 where they attach to a connector for transmitting themeasured values to the indicator such as indicator 40 of FIG. 1. Awindow or cutout 425 (or 425′) is formed in the marker band 422 toenable the sensor 412 to communicate with the blood to measure the pHlevel (or oxygen level) or other parameter as described herein. In theembodiment of FIG. 20A, a radial cutout extending along an arcuateportion of the circumference is provided, although other shapes,lengths, etc. of the cutout are also contemplated. In an alternateembodiment, an axial (longitudinal) cutout 425′ could be provided in themarker band extending along a partial or entire length of the markerband. (See e.g., FIG. 20B). As noted above, the marker band 422 iscomposed of a radiopaque material. One example of a material that can beutilized for the marker band 322 is nitinol, however, other materialscan also be utilized. As noted above, by placing the sensor inside theradiopaque marker band, the user can know the location of the sensor 412by the location of the marker band. A cap 424 such as epoxy material isfitted on the distal end of marker band 422 to cover the distal end andprovide a smooth atraumatic closed rounded surface.

In the alternate embodiment of FIG. 21, the elongated device 430 isidentical to device 400 of FIGS. 15-20 except for the additional cutoutor depression in the tubular portion (hypotube) 432. That is, positionedproximal of outer radiopaque coil 434 (identical to coil 420 of FIG. 15)which is seated over the reduced diameter distal portion of tubularportion 432, tubular portion 432 has a reduced diameter region 436 toaccommodate (mount) a vascular implant, such as a stent or stentretriever for example, for delivery to the target site. The reduceddiameter region 436 is shown just proximal of the reduced diameterregion of the tubular portion 432 over which the coil 434 is mounted.The device 430 includes a rounded tip 440 and a marker band 438 whichcarries the sensor therein as in the embodiment of FIG. 15. Note a softcover can be placed over the tubular portion 432 for delivery which canbe withdrawn once the tubular portion is at the target site to enableexpansion of the vascular implant from its collapsed (reduced diameter)configuration for insertion to its expanded configuration for placementwhen exposed from the confines of the cover. The cover can in someembodiments have a softer tip to increase flexibility of the tip. Anadditional marker band 442 can be provided on tubular portion 432 in asimilar manner as in the embodiment of FIG. 22. In FIG. 22, theadditional marker band 442 is shown proximal of the reduced diameterregion 436′. This proximal marker band can help provide an indication ofthe vascular implant location. In all other respects, the elongateddevice 430′ of FIG. 22 is identical to device 430 of FIG. 21 andcorresponding parts/components, e.g., hypotube 432′, coil 434′, distalmarker band 438′ (with a sensor positioned therein) and tip 440′, havebeen given “prime” designations for ease of identification.

In the alternate embodiment of FIG. 23, flexible elongated device 443has a tubular portion 444 which supports a distal radiopaque coil 448and a proximal radiopaque coil 445. A region 450 of the tubular portion444 between coils 445 and 448 is exposed. Supported (carried) within theregion 450 is a sensor. The region 450 has a cutout or window 452 likecutout 425 to enable communication between the sensor and the blood tomeasure the aforedescribed parameters in the manner described above. Theclinician is informed of the location of the sensor since it is betweenthe two radiopaque coils 445, 448. The device has a rounded tip or cap454 similar to tip or cap 424 of the embodiment of FIG. 15.

The use of the devices 400, 430, 430′ and 443 is the same as describedherein to measure the pH of the blood to determine the condition of thevessel, with the pH reader providing an indication of the measured pH.

Note the devices 400, 430, 430′ can also be used for carrying a densitysensor within the marker band (or adjacent the marker band as in device443) such as the density sensors described above. They can further beused for the aforedescribed oxygen sensors. Additionally, temperaturesensors can be carried by the device. Thus, for example, the densitysensor can be positioned within the marker band to provide theadvantages described above. Wires, a manometric tube, etc. extend withinthe tubular portion for connection to the reader as described above.

In an alternate embodiment, the sensor, e.g., chip, is encased in apolymeric case rather than in a radiopaque marker band and is injectionmolded around the tip of the tubular portion to extend distally thereof.Thus, like the maker band 422, the case (and sensor) would extend distalof the tubular portion providing more space for the sensor therein. Thecase could be injection molded around the hypotube or around the coiland hypotube over which the coil is positioned. A radiopaque elementcould be added to the polymeric case for radiopacity.

FIGS. 14A-14D illustrate one method of use of the present inventionillustratively showing the guidewire system of FIG. 6B. In this system,the health of the vasculature is assessed by measurement of the pH levelof the blood downstream of the clot so that a) a determination can bemade as to how the blood clot can be treated, including whether theblood clot should even be removed; and b) a determination can be made asto how blood flow should be restored.

FIG. 14A shows a conventional introducer catheter 300 inserted throughthe femoral artery to provide access to the vascular system. Aconventional guide catheter 302 is inserted through the introducercatheter 300 and advanced through the vascular system to or adjacent thetargeted cerebral artery, e.g., advanced to the neck region of thepatient. The guidewire of the present invention, such as guidewire 50,is inserted through the guide catheter 302 and advanced adjacent theblood clot C as shown in FIG. 14B. (Note the coupler and reader are notshown in FIGS. 14A-14D) The guidewire 50 is then advanced past the clotC to a position downstream of the blood clot (occlusion). The pH levelof the blood downstream of the blood clot is measured by the pH sensoras described above (or alternatively by the oxygen sensor if an oxygensensor is utilized) and the reader provides a readout of the pH level.Based on this reading, the user is made aware of the pH level of thevessel downstream of the clot C, and thus the health of the vessel. Thisenables the user to determine, e.g., based on comparison to apredetermined pH level, if intravenous thrombolytic therapy, e.g.,injection of drugs to break up the clot, aspiration or mechanicalthrombectomy to grasp and remove the clot, is the better treatmentmethod, or whether removal of the blood clot is too high risk andtherefore should not be removed. The reading also enables the user todetermine the effect of blood flow on the vessel downstream of the clotonce the blood clot is removed and blood flow is restored.

FIG. 14C illustrates the next step of inserting a microcatheter 304 overthe guidewire 50. The microcatheter selected is based on the health ofthe vasculature. For example, in FIG. 14C, a mechanical treatment isselected and the microcatheter 304 having a mechanical thrombectomydevice 306 such as a stent-like device is inserted over the guidewire50. Note the mechanical thrombectomy device 306 has an expandable stentstructure which when expands captures clot which is removed as the stentis collapsed and withdrawn with the catheter. However, other mechanicalthrombectomy devices can be utilized such as motor controlled rotationalwires. In the method shown in FIG. 14C, the vasculature has beendetermined to have a low pH level, for example, below a pH level of 7,or another predetermined level, so the microcatheter selected alsoincludes structure to provide slow reperfusion post clot treatment. Morespecifically, microcatheter 304 has an inflation lumen 308 and aninflatable balloon 310 positioned at a distal end. The microcatheter 304is advanced distal of the blood clot C and the balloon 310 is inflatedvia inflation fluid through lumen 308 prior to, during or after removalof the clot C as shown in FIG. 14C. In this manner, as the device 306removes the clot C, the blood flow is controlled, i.e., full blood flowis not immediately restored. The balloon 310 can be slowly and partiallydeflated to gradually restore full blood flow as the pH level rises asdetermined by the continued measurement of the pH level of the blood bythe sensor of the guidewire 50. With the pH level returned to a safelevel, the balloon can be deflated and the microcatheter 304 removedwith blood flow fully restored. Note the guidewire 50 can be removedfrom within microcatheter 304 prior to use of the device 306 to removethe blood clot so as not to interfere with the device 306. It canperiodically be reinserted within microcatheter 304 to measure the pHlevel of the blood. In alternate embodiments, the guidewire 50 can beleft in place within the microcatheter so the sensor at the distal endcan continuously or periodically measure the blood pH. As can beappreciated, in this method, neither a guidewire nor catheter exchangeis necessary. In some alternate embodiments, the microcatheter caninclude the pH sensor so the guidewire could be removed and need not bereinserted for later measurement. As can be appreciated, in this methodneither a guidewire nor catheter exchange are necessary.

Although the balloon of FIG. 14C is shown distal of the blood clot, itis also contemplated that the balloon can be positioned on themicrocatheter proximal of the blood clot as in FIG. 14E. As shown, aballoon 311 can be positioned on microcatheter 304′ in addition to or inlieu of balloon 310 to control restoration of blood flow. Alternatively,the guide catheter can have a balloon at a distal end which isinflatable at a position proximal of the blood clot (FIG. 14F). Asshown, balloon 303 is positioned on guide catheter 302′ and can beprovided in addition to or in lieu of balloon 310 (and/or balloon 311).The balloons of these embodiments would block or reduce blood flow untilrestoration of full blood flow is desired. Thus, such balloons can beexpanded proximal and/or distal of the blood clot to control blood flow.

In the alternate embodiment of FIG. 14D, the method of FIGS. 14A-14C isthe same except a microcatheter 312 different than microcatheter 306 isutilized when a determination is made, based on a pH level below apredetermined level, e.g., below a pH level of 7, or anotherpredetermined level such as the levels discussed above, that slowreperfusion during or after blood clot treatment (removal) is warranted.Microcatheter 312 has a lumen 314 for injection of cryogenic fluid.Injection of this cooling fluid cools slows the blood flow to provide analternate method of slowly restoring blood flow post clot removal. Theguidewire 50 can be removed from within microcatheter 312 prior to useif desired and periodically reinserted if desired, or alternatively leftin place as discussed above. The microcatheter can in an alternateembodiment include a pH sensor.

Note if an interventional therapy treatment is utilized, the catheter toinject the drugs for blood clot removal can have a separate inflationlumen and an inflatable balloon to function to regulate blood flow inthe same manner as balloon 310 of microcatheter 304 or can have a lumen,either the same or different from the lumen to inject the drugs, toinject the cooling fluid to slowly restore blood flow in the same manneras microcatheter 312.

Note a comparison is made of the pH level to a predetermined level todetermine how to treat the clot. A comparison is also made of the pHlevel to a predetermined level to determine if slow reperfusion iswarranted. These predetermined levels can be the same or differentlevels. Examples of such predetermined levels are discussed above, aswell as other levels, are fully applicable to these embodiments of FIGS.14A-14F as well.

Further note that the microcatheter can be inserted over the guidewirebefore or after pH level is measured. Also, in alternate embodiments theguide catheter can be provided with a mechanical thrombectomy device toremove the clot and/or a balloon or cooling fluid lumen so that aseparate catheter, e.g. microcatheter 312, need not be utilized.

Also note that microcatheters 304 and 312 are examples of catheters thatcan be utilized to slow reperfusion, it being understood, that othercatheters with other structure to slow reperfusion are contemplated.Additionally, use of the balloon or cooling fluid disclosed herein canbe used on catheters other than catheters with the structure ofcatheters 304 and 312.

In the embodiment of FIG. 1 where a catheter rather than a guidewire isutilized to measure pH levels of blood, a microcatheter with a balloonor lumen for injection of cryogenic fluid can utilized to slowly restoreblood flow in the manner described above.

Note the aforedescribed sensors thereby provide a means for measuringthe blood pH which can be utilized to determine the health of thevasculature, the reader provides a means for indicating the sensed pH,the microcatheter provides a means for removing the clot and theinflatable balloon or cryogenic fluid provides a means for controllingthe rate of blood flow after clot removal.

Note the systems described above assess the blood distal of the bloodclot, however, it is also contemplated that assessment of the blood viapH measurement can be performed adjacent the blood clot but proximal tothe blood clot in the aforedescribed closed or substantially closedsystem. Such reading proximal the blood clot can also provide a readingof the vessel vitality adjacent the clot and therefore distal the clot.

Note the aforedescribed systems can alternatively measure oxygen levelof the blood rather than pH level as discussed above to determine thehealth of the vasculature and determine treatment as in FIGS. 14A-14F.

The systems are described herein mainly for use with treating bloodclots. However, any of the systems disclosed herein can also be used inother clinical applications. For example, one alternate application isto assess the condition of an organ, e.g., a transplanted organ such asa kidney, by measuring the pH of blood within the vasculature of theorgan to assess the condition of the organ. That is, an assessment of pHlevel in a vessel within the organ to assess vessel vitality willprovide an indication of the pH level of the organ to determine thevitality of the organ and whether steps need to be taken to address theorgan going bad or potentially not functioning properly.

Clot Determination and Clot Removal Tracking

As noted above, the present disclosure provides a system to identify aparameter such as the composition of a blood clot in a vessel which willenable the physician to scientifically determine the clot makeup anddetermine the best course of treatment from the available tool sets.This can be achieved in accordance with one embodiment using ultrasound.Such ultrasound system can also be used during the procedure and/orafter the procedure to measure clot density so the clinician candetermine if the blood clot has effectively been reduced or sufficientlyremoved from the vessel.

In the embodiment utilizing ultrasonic waves, the density of the clotcan be estimated, in vivo, by determining the time it takes for anultrasonic sound wave to “bounce” back from the clot. The longer thesignal takes to return, the less dense the clot is. That is, anultrasound signal will return more quickly when interacting with adenser substrate. The average densities of traditional “soft” clot andthe denser fibrin clot is determined to provide predeterminedparameters, and then the system of the present disclosure compares thesignal generated by the ultrasonic wave to these parameters to informthe physician of the type of clot. Thus, the system utilizes a logiccircuit to determine the makeup of the clot quickly, efficiently andeffectively. By way of example, a soft clot can be assigned a numeral 1and a hard clot assigned a numeral 10, and the clot density measured toassign a value within this range so the physician would first beinformed of the type of clot before taking treatment steps, such asremoval of the clot. In other words, the measured average densities ofboth soft clot and fibrin will provide a “baseline” incorporated intothe logic-circuit which will determine, in vivo during the surgicalprocedure, which clot type is present within the vessel. Other numericvalues or indicators are also contemplated to indicate varyingdensities. Thus, the predetermined baseline and the assessment inaccordance with this baseline provide a means to provide a density valuefor the clinician thereby providing a convenient method for thephysician to asseses the blood clot.

In the system, to generate and provide a digital or analog readout ofthese ultrasound signals a piezoelectric signal transducer can be used.Piezoelectric materials are crystalline structures which undergo amechanical deformation when a certain voltage is applied to the crystal.This property is used in conjunction with an applied AC voltage appliedto the crystal. As the AC voltage is applied to the piezo-material itwill deform and generate a sound wave. Likewise, when a mechanical loadis placed on the piezoelectric crystal a small voltage is generated.This property is used to convert an ultrasonic signal into a measurablevoltage. The piezoelectric crystal has a specific voltage/frequencyrelationship which can be used to convert between the two.

Because of these unique properties, the same piezoelectric transducerwhich generates an ultrasonic signal can also be used to receive thereflected signal returning from a substrate. Utilizing these propertiesthe ΔT (change in time) can be determined between the sent signal andthe received signal by having predetermined the average ΔT for bothnormal and fibrin clots; the designed logic circuit will be able todetermine which clot is present.

This ultrasonic signal is sent from within the vasculature to ensurethat interference from cranial tissues, muscle, bone, etc. do not affectmeasurements. The size and shape of the piezoelectric crystal willdetermine the distance at which the measurement can be best made.

Turning now to the system of FIGS. 9A-12B, a system for determining thetype of clot is illustrated, with FIG. 9A illustrating an embodimentwhere the density sensor (utilizing ultrasound as described above) is ona catheter and FIG. 11A illustrating an embodiment where the densitysensor (utilizing ultrasound) is on a guidewire. It is also contemplatedthat a density sensor can be positioned on the catheter and on theguidewire, and it is also contemplated that one or more density sensorscan be positioned on the catheter and one or more density sensors can bepositioned on the guidewire. This enables more than one region of theclot to be measured which could be beneficial in large clots.

Turning more specifically to the system of FIGS. 9A, 9B and 10, catheter110 has a proximal portion 112 and a distal portion 114. The cathetertube 116 is sufficiently flexible to navigate the small vessels whilehaving some rigidity to enable it to be directed around the curves ofthe vasculature. An RHV 120 is attached to the catheter hub 122 andincludes a side arm 124 for fluid injection and/or aspiration. Coupler130 is attached to the catheter 110, and is connected to cable 134 whichis connected to density reader (meter) 140. In one embodiment, thecoupler 130 can be the same as coupler 30 of the embodiment of FIG. 1and can be u-shaped with an opening between the legs of the “u”dimensioned to frictionally clamp onto the outer wall of the catheter110. That is, the coupler can be in the form of a U-shaped clip with theradius of the U smaller than that of the outer wall of the catheter soit flexes outwardly when placed over the strain relief of the catheterand then is frictionally retained on the catheter. In anotherembodiment, a second connector half is placed opposite the connector toform a 360 degree clip or clamp surrounding the outer wall of thecatheter to retain the connector (coupler) on the catheter 110. Othermethods of attachment are also contemplated such as magneticattachments. A cable 134 is connected to the coupler at one end 135 andconnected at the opposing end 136 to density reader 140. As shown, thecoupler 130 is attached to the region of catheter 110 just distal of hub122, although other locations are also contemplated.

The density sensor 126 is positioned at the distal portion 114 of thecatheter 110, at the distalmost tip 115 and is electrically coupled tocable 134 via a pair of wires (not shown) extending from the sensor 126to the coupler 130 and/or cable 134. The wires can be embedded in a wallof the catheter 110 or alternatively extend through a lumen in thecatheter 110. The sensor 126 in the illustrated embodiment is at thedistalmost tip but alternatively could be spaced from the distalmost endso the catheter tip can extend past the clot during use while the sensoris positioned within the clot. The sensor can be positioned on an outerwall of the catheter 110, extending circumferentially around 360degrees. The sensor can also be positioned inside the catheter 110,either internal of the inner catheter wall or alternatively embedded inthe wall of the catheter. The sensor can alternatively be positionedwithin a marker band on the catheter, with a portion of the marker bandremoved (a cutout formed) to expose the sensor as in FIG. 20A forexample. The sensor can be positioned within the marker band in the samemanner as the sensor in FIGS. 15-22. Wires (not shown) connect thesensor to the coupler 130 and/or cable 134.

The density reader 140 provides an indicator device and contains an onoff switch 142. A reading 144 provides a visual indication as a numericvalue representative of a comparative density as explained above. FIG.10 shows a density reading of “5” by way of example, indicating a clotdensity midway between the outer soft clot and outer hard clot range. Asnoted above, these numerical values are assigned in accordance withpredetermined density averages assigned a representative numeric valuewithin a range of values. Connector (coupler 120) is wired to the reader140 which provides a reading of the clot type based on the signalreceived from the sensor 126 in response to the ultrasonic signal causedby the ultrasonic waves applied to the clot. Thus, the reader provides ameans to display the density, the density displayed in a convenientdisplay as the system processes the time change in sent and receivedsignals to assess density, conducts via an algorithm, a comparativeanalysis to predetermined density value (e.g., a value of zero), or topredetermined density ranges and then converts it to a numeric valuerepresentative of the density within a given range of densities. Thus,the clinician does not need to conduct additional analysis to interpretthe measured clot density but can simply rely on the assigned numericalvalue. This is illustrated in the flow chart of FIG. 24A.

In use, the catheter 110 can be inserted utilizing known methods, e.g.,through a femoral approach or a brachial approach, and advanced throughthe vascular system to the desired treatment site, e.g., the cerebralartery A. The catheter tip 115 is advanced past the blood clot C (seee.g., FIG. 9B) so the sensor 126 is located within the blood clot. Thesensor 126 is activated, using ultrasonic waves to measure density, withthe density reader providing a visual density indication so the user candecide the optimal way to treat the clot.

FIG. 11A illustrates an alternate embodiment for measuring densityutilizing a sensor on a guidewire instead of the catheter as in FIG. 9A.The guidewire provides a reduced profile measurement system. It alsoprovides a more flexible system to navigate tortuous vessels. Also, bybeing smaller it can be inserted more distal within the cerebralvasculature. It could also be more steerable and could traverse the cloteasier. In some embodiments, by way of example, the outer diameter ofthe guidewire can be between about 0.010″ and about 0.032″, althoughother ranges of sizes are also contemplated. In some embodiments, theouter diameter can be about 0.014″.

Guidewire 150 has a proximal portion 152 and a distal portion 154. Theguidewire 150 is sufficiently rigid to navigate the small vessels whilehaving some rigidity to enable it to be directed around the curves ofthe vasculature. In one embodiment, the guidewire is hollow to form alumen and the wires run through the lumen from the sensor to theconnector. The wires are preferably insulated. In another embodiment,the guidewire is a solid core and a polymeric jacket contains theinsulated wires on an outer surface of the guidewire. The guidewire isillustrated within a lumen of a catheter 170 having a RHV 174 attachedto the proximal end. The RHV 174 is attached to the hub 172 of catheter170 and includes a side arm 175 for injection and/or aspiration. Coupler180 is attached to the guidewire 150, and is connected to cable 183which is connected to density reader 140. The density reader 140 can bethe same and function in the same manner as in the embodiment of FIG. 10described above. In one embodiment, the coupler is the same as coupler80 of FIG. 7 and is u-shaped with an opening in the “u” dimensioned tofrictionally clamp onto the wall of the guidewire 150. A two partconnector (coupler) as described above can also be utilized. Othermethods of attachment are also contemplated such as magneticattachments. Cable 183 is connected to the coupler 180 at one end 185and connected at the opposing end 186 to meter (reader) 140.

Density sensor 156 is positioned at a distal end of the guidewire 150,either at the distalmost tip or spaced from the distalmost tip as shownin FIG. 11B, and is electrically coupled to coupler 180 and/or cable 183via a pair of wires (not shown) extending from the sensor 156 to thecoupler/cable. The wires can be embedded in a wall of the guidewire 150or alternatively the guidewire can have a lumen or channel through whichthe wires extend. In the embodiment of FIGS. 11A and 11B, the sensor 156is positioned on an outer wall of the guidewire 150, extendingcircumferentially around 360 degrees. The sensor can also beincorporated into a marker band at the tip of the guidewire 150. In analternate embodiment, the sensor can be positioned inside the guidewire150, either internal of the inner wall of the guidewire in the samemanner as in the embodiment of FIG. 8B, or alternatively embedded in thewall of the guidewire. In some embodiments, the guidewire has a markerband with a cut or removed portion to expose the sensor mounted withinthe marker band as in FIG. 20A for example. In some embodiments by wayof example, the marker band can have an outer diameter of about 0.014″and an inner diameter of about 0.012″. Other dimensions are alsocontemplated. The catheter 170 through which the guidewire extends canhave a marker band for imaging. The sensor can be positioned within themarker band in the same manner as the sensor in FIGS. 15-22. Note inFIG. 11A, the guidewire 150 is positioned with the sensor in the clot Cand the catheter 170 is positioned in a cerebral artery A proximal ofclot C.

In use, the density sensor 156 is activated to selectively measure thedensity of the blood clot and with switch 142 turned on, densityindication is provided. The density measurement, comparative analysis,conversion to numeric value, etc. is the same as described above (seealso FIG. 24A). Note the guidewire 150 can be inserted utilizing knownmethods, e.g., through a femoral approach or a brachial approach, andadvanced through the vascular system to the desired treatment site, e.g.the cerebral artery. In a preferred method, first an introducer isplaced in the femoral artery, and a large guidewire and guide catheterare advanced to the carotid artery. The large guidewire is removed, andreplaced with a microcatheter 170 and a smaller dimensioned guidewire150 of the present invention which contains sensor 156. The catheter tip171 is advanced past the blood clot C. The guidewire 150 is positionedin the clot and in some embodiments the catheter 170 is withdrawnproximally to expose the sensor 156 within the clot C to measure thedensity of the clot (in other embodiments, the sensor is exposed so thecatheter does not need to be withdrawn). The sensor 156 transmits themeasurement through the wires extending in guidewire 150 back to thecable 183 which in turn transmits it to the reader 140. Proper treatmentapproaches for the treating the blood clot can then be better selected.That is, the reader 140 is used to indicate density measurement so thephysician can determine the optimal way to treat the clot. For example,if density measurement determines a soft clot, aspiration can beutilized (mechanical devices are generally not designed for soft clot);if a hard clot, aspiration might not be effective to remove the clot soa mechanical removal device can be utilized. Without densitydetermination, the clinician in certain instances might need to tryseveral different devices to effect satisfactory clot removal whichcould be more expensive and is time consuming due to withdrawal andinsertion of different devices. In short, the pre-treatment densitydetermination provides the clinician with additional knowledge tooptimize and increase the efficiency of clot removal.

The system for measuring density to determine approaches to treating theclot, using either the aforedescribed catheter system or guidewiresystem, can also be utilized additionally or alternatively, to determinethe density of the clot after the clot removal procedure has beenselected and commenced. Clot removal can be performed for example by athrombectomy device which has a mechanical component to break up theclot as it is rotated, by an aspiration device which aspirates the clot,or by other methods. During the procedure, as the clot is removed, thedensity of the clot will decrease. In addition, the length of the clotwill decrease as the clot is removed. By taking measurements of the clotduring the procedure, an indication can be provided to the clinician(user or physician) of the status of clot removal. Further, eitheralternatively or in addition, the measurement can be used at the end ofthe blood clot removal procedure. That is, if the clinician believes theclot has been sufficiently removed, before ending the procedure, thedensity measuring system can be utilized to determine the clot densityand thus confirm the clot has been effectively removed.

More specifically, at the start of the procedure, the density of theclot can be determined by ultrasound waves as described herein toprovide an initial value. In one embodiment, this initial value can bethe value described above which provides a numerical value forcomparison to a predetermined baseline. At any time during theprocedure, the user can activate the system to generate the ultrasoundwaves to measure the density of the clot by measuring the transmittedand received signals as described above. This measurement can becompared to the initial value to ensure the density is decreasing. Incertain embodiments, once a certain reduced density level is reached,the clinician is informed that a sufficient portion of the clot has beenremoved. Such density measuring system avoids the need for the clinicianto inject contrast which can in certain instances have the adverseeffect of re-compacting the clot.

In some embodiments, an initial density value determined at the start ofthe procedure (represented by “X1” in FIG. 25) can be a valuerepresentative of the actual density of the clot. Optionally, anotherinitial value (represented by “Y1” in FIG. 25) can also berepresentative of the length of the clot. In this embodiment, these twoinitial values can be recorded and/or indicated on the density reader ofFIG. 25, preferably displayed in a window(s) 145 of reader 140′ separatefrom the comparative density numeric value 144′, e.g. “5”. When duringthe procedure, the clinician desires to know the clot density and/orlength (since a reduction in the length is indicative of the clot beingreduced), these measurements can be taken and indicated on reader 140′,represented by X2 and Y2, respectively, for comparison to the respectiveinitial values X1, Y1. As the new values (X2 . . . Xn, Y2 . . . Yn)decrease relative to the initial values, the clinician is informed thatthe clot is being reduced, and after a period of time, indicate that theclot has been effectively removed.

A method of using the system to determine a state of blood clot removal(i.e., tracking removal) from a vessel of a patient, with reference tothe flow chart of FIG. 24B, can encompass the steps of inserting anelongated flexible member, e.g., a guidewire or a catheter, having adensity measuring component, through vasculature of the patient andadjacent the blood clot, measuring a density of the blood clot to obtaina first value (the first value representative of a density measurementpre-treatment), and to determine a blood clot removal approach,inserting a clot removal device, e.g., a mechanical thrombectomy deviceor an aspiration device, to remove the blood clot, and aftercommencement of treatment of the blood clot (by the clot removal device)measuring the density of the blood clot to obtain a second (subsequent)value so that the second value can be compared to the first value toinform the clinician of the extent of removal of the blood clot from thevessel. Obtaining the second value can occur during the treatment orwhen the clinician believes the clot has been sufficiently removed,e.g., by viewing the collection bag, and therefore believes thattreatment can be terminated. Measurements, if desired, can be repeatedlytaken during the procedure, i.e., as portions of the clot are removed,to provide real time indication (assessment) of the blood clot removal.As noted above, these values can be displayed on a display to provide avisual indication and/or comparative analysis of the current status ofthe blood clot. Once the comparison of the subsequent measurement to theinitial measurement indicates the blood clot has effectively beenremoved, the procedure can be terminated and the clot removal device andelongated flexible member with sensor removed from the body.

To further assist the clot treatment determination, the system andmethod can optionally include the steps of a) determining a length ofthe blood clot prior to commencement of the procedure to remove theblood clot and b) determining the length of the blood clot aftercommencement of the procedure to remove the blood clot to determine adecrease in length of the blood clot. Such length determination can bemade repeatedly if desired during removal of portions of the blood clotand/or when the clinician believes the clot has been removed.

As noted above, this system and method can be utilized in conjunctionwith a catheter or guidewire having a sensor for measuring pH level (oroxygen of other parameter) and an indicator to the user of such level ofthe blood to enable the user to determine a pH level (or oxygen or otherparameter) of the vessel downstream of the blood clot utilizing thesystems described herein for a) selection of a treatment method toremove the blood clot, including non-removal; and/or b) a determinationwhether slow reperfusion during and/or after removal of the blood clotis warranted.

Note that the flexible devices 400, 430, 430′ can be used in the samemanner as described herein to measure the density of the clot todetermine the condition of the vessel using a density sensor positionedwithin the marker band (or adjacent as in device 443), with the densityreader providing an indication of the density.

Combination of Systems

It is contemplated that the system for determining clot density (orother clot parameter) and the system for measuring the blood pH (orother blood parameter such as oxygen) can be used together. In suchsystem, both the density sensor and pH sensor (or oxygen sensor) alongwith a density and pH (or oxygen) reader are provided. Such system isshown in the embodiment of FIGS. 12A-13. The system can also includemeasuring density to track blood clot removal as described above and thereader described below can be modified to indicate such measurement(s)as in reader 140′ of FIG. 16.

Catheter 210 has a proximal portion 212 and a distal portion 214. Thecatheter tube 216 is sufficiently flexible to navigate the small vesselswhile having some rigidity to enable it to be directed around the curvesof the vasculature. An RHV 220 is attached to the catheter hub 222 andincludes a side arm 224 for fluid injection and/or aspiration. Coupler230 is attached to the catheter 210, and is connected to cable 234 whichis connected to pH reader (meter) 241 of reader 240. Reader 240 providesboth a pH reading and a density reading. Although shown as a singlereader (meter), it is also contemplated that separate meters, such as inFIGS. 2 and 10 could be provided. In one embodiment, the coupler 230 isidentical to the embodiment of FIG. 4, being U-shaped with an opening inthe “u” dimensioned to frictionally clamp onto the outer wall of thecatheter 210. Alternatively, a second connector (coupler) half asdescribed above can be utilized. Other methods of attachment such asmagnetic attachment are also contemplated. Cable 234 is connected to thecoupler 230 at one end 235 and connected at the opposing end 236 toreader 241. As shown, the coupler 230 is attached to the region ofcatheter 210 just distal of hub 222, although other locations are alsocontemplated.

The pH sensor 226, identical to the sensor of FIG. 1, is positioned atthe distal portion 214 of the catheter 210 and is electrically coupledto cable 234 via a pair of wires (not shown) extending from the sensor226 to the coupler 230 and/or cable 234. The wires can be embedded in awall of the catheter 210 or alternatively extend through a lumen in thecatheter 210. In the embodiment of FIG. 12A, the sensor is positioned onan outer wall of the catheter 210, extending circumferentially around360 degrees in an identical manner as shown in FIG. 3A. The sensor canalso be incorporated into or positioned within a marker band at the tipof the catheter 210 in the same manner as in FIGS. 16-22. In thealternate embodiment, the sensor can be positioned inside the catheter210 (similar to sensor 26′ of FIG. 3B), either internal of the innercatheter wall or alternatively embedded in the wall of the catheter. ThepH sensor can be positioned at the distalmost tip as shown oralternatively spaced proximally of the distalmost tip. Wires connect thesensor 236 to the coupler 230 and/or cable 224.

The pH reader 241 contains an on off switch 248 to selectively provide areadout of the measured pH. A reading 244 provides a visual indication,as a numeric value, of the measured pH of the blood for the user todetermine the pH of the vasculature. A pH of 6.9 is shown by way ofexample.

Guidewire 250 has a proximal portion 252 and a distal portion 254. Theguidewire 250 is sufficiently rigid to navigate the small vessels whilehaving some rigidity to enable it to be directed around the curves ofthe vasculature. The guidewire 250 is illustrated within a lumen ofcatheter 210. Coupler 280 is attached to the guidewire 250, and isconnected to cable 283 which is connected to density reader 245 ofreader 240. In one embodiment, the coupler 280 is the same as coupler 80of FIG. 7 and is u-shaped with opening in the “u” dimensioned tofrictionally clamp onto the wall of the guidewire 250. Alternatively, asecond connector (coupler) half as described above can be utilized.Other methods of attachment such as magnetic attachment are alsocontemplated. Cable 283 is connected to the coupler 280 at one end 285and connected at the opposing end 286 to reader (meter) 245.

A density sensor 256, which is identical to sensor 156 of FIG. 11B, ispositioned at a distal portion of the guidewire 250, spaced proximallyof the distalmost tip, and is electrically coupled to coupler 280 and/orcable 283 via a pair of wires (not shown) extending from the sensor. Thewires can be embedded in a wall of the guidewire 250 or alternativelythe guidewire can have a lumen or channel through which the wiresextend. In the embodiment of FIG. 12A, the sensor 256 is positioned onan outer wall of the guidewire 250 in the same manner as sensor 156 ofFIG. 11B, extending circumferentially around 360 degrees. The sensor 256can also be incorporated into a marker band at the tip of the guidewire250. In an alternate embodiment, the sensor can be positioned inside theguidewire 250, either internal of the inner wall of the guidewire in thesame manner as shown in FIG. 8B, or alternatively embedded in the wallof the guidewire. The sensor can be positioned within the marker band inthe same manner as the sensor in FIGS. 15-22. The catheter 210 throughwhich the guidewire 250 extends can have a marker band. Note in FIG.12A, the catheter 210 and guidewire 250 are positioned in a cerebralartery A distal of clot C. In use, the catheter 210 can be withdrawnwith respect to the guidewire 250 to expose the density sensor 256within the clot as shown in FIG. 12B where the density sensor 256 isproximal of the distal tip (in other embodiments, the sensor is exposedso the catheter does not need to be withdrawn). In the embodimentwherein the density sensor 256 is at the distalmost tip, the guidewire250 would be withdrawn further proximally until the distalmost tip (andsensor) is positioned in the clot.

In the embodiment where the pH sensor is on the guidewire (as in theembodiment of FIG. 6) and the density sensor is on the catheter (as inthe embodiment of FIG. 9A), the catheter need not be withdrawn. Thedensity sensor 256 in some embodiments can be positioned proximal of thepH sensor 226 during use since the density sensor is exposed on theoutside of the catheter to measure the blood clot parameter and the pHsensor is exposed on the guidewire to measure the blood parameterdownstream of the blood clot. In use, the density sensor is activated tomeasure clot density and switch 247 of the density reader 245 of reader240 is turned on to provide a visual numeric indication of a relativedensity. Density can be measured at various times during the procedureto track clot removal as described above. The pH sensor is activatedeither simultaneously, or at a different time, so pH reader 241 providesa visual numeric indication of blood pH.

It is also contemplated that in some embodiments a pH sensor (or oxygensensor) and a density sensor can both be positioned on a singleguidewire or a single catheter.

Note the guidewire 250 can be inserted utilizing known methods, e.g.,through a femoral approach or a brachial approach, and advanced throughthe vascular system to the desired treatment site, e.g., the cerebralartery. In one method, first an introducer would be placed in thefemoral artery, and a large guidewire and guide catheter would beadvanced to the carotid artery. The large guidewire is removed, andreplaced with a microcatheter 210 which contains a pH (or oxygen) sensor(or alternatively a density sensor) and a smaller dimensioned guidewire250 of the present invention which contains sensor 256. The catheter tip271 is advanced past the blood clot C. The sensor 256 of guidewire 250is positioned in the clot so the sensor measures the density of the clotand transmits the measurement through the wires extending in guidewire250 back to the cable 283 which in turn transmits it to the densityreader 245 of reader 240. (In the embodiment where the catheter containsthe density sensor, the guidewire can contain the pH (or oxygen) sensor.The pH sensor 226 is positioned distal (downstream) of the blood clot tomeasure pH of the blood distal of the clot and transmit it via wires tothe cable and pH reader 241. As noted above, the closed (orsubstantially closed) system advantageously enables the user todetermine the vasculature condition by measuring the blood pH ratherthan the pH of the vasculature (and surrounding tissue) itself. Propertreatment approaches for treating the blood clot (or not treating theclot as discussed above) and/or restoring blood flow can be betterselected. The density reading provides information on the blood clotitself which can be utilized to determine blood clot treatment. Thereader can also include readings of density after treatment commences sothe user can determine the status of blood clot removal. As noted above,an oxygen sensor can be used in the closed or substantially closedsystem to determine the vasculature condition.

Note that the devices 400, 430, 430′ and 443 can be used in the samemanner as described herein to measure the pH of the blood to determinethe condition of the vessel and to measure the density of the clot, withone or both of the sensors within the marker band and the pH reader anddensity reader providing an indication of such measurements. Atemperature sensor to measure temperature of the vasculature could alsobe provided on the device or within the marker band.

Note the couplers described herein are preferably coupled to thecatheter or guidewire prior to their insertion. However, alternatively,coupling can occur subsequent to insertion to facilitate maneuverabilityto the target site.

While the above description contains many specifics, those specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of preferred embodiments thereof. Thoseskilled in the art will envision many other possible variations that arewithin the scope and spirit of the disclosure as defined by the claimsappended hereto.

1-20. (canceled)
 21. A medical device for insertion into a body of apatient, the medical device comprising: a flexible elongated tubularportion configured and dimensioned for insertion into the body of thepatient, the elongated tubular portion having a proximal portion, adistal portion having a distalmost edge and a lumen formed therein; amarker band, at least a portion of the marker band positioned distallyof the distalmost edge of the tubular portion so as to extend distallytherefrom, wherein the marker band is exposed from the tubular portionand has an internal diameter larger than an internal diameter of thetubular portion from which it extends; and a sensor positioned withinthe marker band, wherein the sensor is positioned distally of thedistalmost edge of the tubular portion.
 22. The medical device of claim21, further comprising a cap at the distal end of the marker band toprovide a smooth surface.
 23. The medical device of claim 21, whereinthe tubular portion comprises a hypotube.
 24. The medical device ofclaim 21, wherein the tubular portion has a first wall thickness and themarker band has a second wall thickness, the second wall thickness ofthe marker band being less than the first wall thickness of the tubularportion.
 25. The medical device of claim 24, wherein the sensorcommunicates with an indicator outside the body of the patient.
 26. Themedical device of claim 24, wherein the first wall thickness is betweenabout 0.002 inches and about 0.004 inches and the second wall thicknessis between about 0.001 inches and about 0.002 inches.
 27. The medicaldevice of claim 21, wherein the tubular portion has a coil positionedthereover forming a first outer diameter and the marker band has asecond outer diameter substantially equal to the first outer diameter.28. The medical device of claim 21, wherein the tubular portion has areduced diameter region having a first outer diameter and the markerband has a second outer diameter greater than the first outer diameter.29. The medical device of claim 21, wherein the marker band has a windowto enable communication of the sensor with the patient.
 30. The medicaldevice of claim 21, wherein the tubular portion has a first reduceddiameter region at a distal region, and a radiopaque coil is positionedon the first reduced diameter region.
 31. The medical device of claim21, further comprising a second marker band positioned proximal of themarker band which has the sensor therein.
 32. The medical device ofclaim 21, wherein the sensor has a wire extending through the lumen ofthe tubular portion.
 33. The medical device of claim 21, wherein thesensor is contained in a microchip and a wire extends through the lumenof the tubular portion.
 34. The medical device of claim 24, wherein thetubular portion has a first reduced diameter region and a second reduceddiameter region formed proximal of the first reduced diameter region tosupport a vascular implant.
 35. The medical device of claim 21, furthercomprising a second sensor to sense a different parameter, the secondsensor connected to a second indicator.
 36. The medical device of claim35, wherein the second sensor is positioned within the marker band. 37.The medical device of claim 21, wherein the sensor includes fiber opticstransmission.
 38. The medical device of claim 21, wherein the tubularportion comprises a hypotube having a martensitic distal region and anaustenitic proximal region.
 39. The medical device of claim 22, whereinthe indicator is configured to be positioned outside the body of thepatient.
 40. The medical device of claim 21, wherein the marker band isattached to the tubular portion by a tab-slot arrangement.